My Samsung tv doesn’t recognize the soundbar, via HDMI after the tv is turned off. I literally have to turn off my power strip and rest everything every time I want sound from the bar. What do I do. The tv recognize the speaker for the first month.
Fron the brief description it is not clear from what date your problem started to occur but careful check when your ST300 applied the 19.0.13 update and when your TV last applied its own software update. At a guess I suspect the HDMI CEC/ARC behaviour on your TV has been updated by an uodae it received, the Soundtouch update i mentioned should not have changed that aspect.
Check the HDMI CEC setting, in the Soundtouch app, select the Speaker (not setup Speaker), cog wheel, Advanced Setup, HDMI CEC and check what setting you have there, if you have ‘Default On’ try setting Alternate On (which allows Soundtouch to turn off with the TV but using the TV remote will not control the soundbar and configure yur TV setting for the ST300 remote instead, check the book of codes included in the box).
I had similar issues to what you mentioned when I set fully automatic HDMI CEC on a Samsung Blu Ray player as the TV and play would fight to control each others devices would switch off autonatically after switching on etc).
You can also try a different HDMI cable just in case.
If nothing else works turn off HDMI CEC on the Soundtouch app and consider connecting via the optical cable supplied.
Powering off your Soundbar frequently should be avoided where possible as it is designed to remain in standby node so a music source can activate it.
If you configure the auto on feature, power cycling the soundbar seems to force that setting to be lost.